In my classroom, I’d probably prefer a more narrow focus — a specific concept over a general math activity. For homework, have students take a photo of parallel lines and a transversal. In class, ask What do you notice?™ Christopher Danielson’s students — future elementary teachers — were asked to photograph a composed unit, which led to a lovely classroom discussion. Dan Meyer kicks the find a positive & negative slope challenge up a notch by holding a steepest stairs competition.